A distributed storage system is actualized by causing a plurality of storage devices and storage control devices that control data access to the plurality of storage devices to be grouped into clusters. The distributed storage system has high system expandability in case of increase in the volume of data to be stored.
Various techniques have been proposed to improve performance of the storage system. For example, a technique is proposed in which resource usage information including a plurality of pieces of information, such as a processor usage rate, is tabulated for a total or for each logical volume number. When any of the tabulated results exceeds a threshold value, a warning is issued.
In addition, for example, a technique has been proposed in which a load factor of a central processing unit (CPU) of a server is monitored based on previous tendencies at all times. Overloaded servers and low-load servers are extracted. For overloaded servers, the content name of a content to which users are concentrated is hidden from a menu list. For low-load servers, the content name and the content are copied from the overloaded server.
Related techniques are disclosed in, for example, Japanese Laid-open Patent Publication No. 2003-296039 and Japanese Laid-open Patent Publication No. 11-25059.
In the distributed storage system, in order to move data between storage devices for the purpose of distributing processing load placed on storage control devices, the data to be moved has to be appropriately selected. However, it is difficult to accurately determine which piece of data, among the plurality of pieces of data stored in the storage devices, is most affecting the load placed on the storage control device. Therefore, a problem occurs in that appropriate selection of data effective for reducing the load placed on the storage control device is difficult.